HAT-P-22
HD 233731
Suspected multiple star system in the constellation Ursa Major
HD 233731, or HAT-P-22, is a suspected multiple star system in the northern circumpolar constellation of Ursa Major. It is invisible to the naked eye, having an apparent visual magnitude of 9.732.[2] This system is located at a distance of 267 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13 km/s.[1]
The stellar classification of the primary is G5V,[3] matching an ordinary G-type main-sequence star. The star has a low level of stellar activity with an estimated age of 9 to 12 billion years old. Its metallicity is twice that of the Sun, unusual for its advanced age.[3] HD 233731 has a similar mass and radius as the Sun, and is spinning with a rotation period of 28.7 days.[3] It is radiating 77%[2] of the luminosity of the Sun from its photosphere at an effective temperature of 5314 K.[3]
A faint stellar companion (2MASS J10224397+5007504) with a red hue is located at an angular separation of 9 arcseconds from the primary.[2] In 2015, a spectroscopic stellar companion was reported with a semimajor axis of less than 33 AU. This star has an effective temperature of 4,000+250
−400 K with a mass of 0.63+0.07
−0.17 M☉.[5]